Univerisity of Texas at Austin, USA
Title: Atomic layer deposition routes to monolithic integration of crystalline oxides on semiconductors
Biography: John Ekerdt
The semiconductor industry faces new challenges in the sub-10 nm era as scaling will no longer dominate performance improvement. New materials provide opportunity to improve performance with minimal architectural overhaul. For example, high-mobility channels of Ge and III-V semiconductors can provide both lower power consumption and faster computing speeds. In certain applications significant advantages are gained by monolithic integration of the oxides directly on the substrates that will host other devices/components. Perovskite oxides offer a wide range of properties from high-k to multiferroic affording the device designer a suite of possibilities, and are particularly important due to their common structure and lattice-matching with common semiconductors. The gallium nitride device applications will require a dielectric to passivate the nitride surface. Atomic layer deposition (ALD) allows for growth of perovskite oxides and rare earth oxides in a chemical deposition process that is scalable and manufacturable. It is possible to grow crystalline perovskites directly on Ge(001) by ALD. Using this approach we have been able to deposit STO, BaTiO3, SrHfO3, Sr(HfTi)O3, and SrZrO3 directly on Ge(001). We will discuss the growth and properties of the perovskite layers directly on Ge(001), and will discuss the interface chemistry and structure that likely controls the interfacial reactions that allow for crystalline film formation. It is also possible to grow crystalline rare earth oxides directly on GaN(0001) by ALD. We report approaches to growing crystalline, hexagonal and cubic Er2O3 on wurtzitic gallium nitride, GaN (0001). As with growth of perovskites on Si and Ge, atomically-thin intermetallic compounds comprised of Group 1 or 2 elements and Group 13-15 elements to facilitate wetting and direct the crystalline growth, in this case the  growth direction of the oxides on GaN (0001). This talk will describe the growth, structures and properties of crystalline oxides grown by ALD.
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